memory_minder.rb

#!/usr/bin/env ruby

command = '/usr/bin/passenger-memory-stats'
memory_limit = 200 # megabytes

def running?(pid)
  begin
    return Process.getpgid(pid) != -1
  rescue Errno::ESRCH
    return false
  end
end

`#{command}`.each_line do |line|
  next unless /(\d+)\s+\d+\s+(\d+\.\d+)\s+MB\s+(\d+\.\d+)\s+MB\s+Rails:/.match(line)
  all, pid, vm_size, private = $~.to_a
  if private.to_i > memory_limit
    puts "#{Time.now}: Killing #{pid}, memory usage == #{private}"
    Process.kill("SIGUSR1", pid.to_i)
    puts "Finished kill attempt. Sleeping for 20 seconds..."
    sleep 20
    if running?(pid.to_i)
      puts "Process is still running, sending term signal"
      Process.kill("TERM", pid.to_i)
      sleep 20
      if running?(pid.to_i)
        puts "Process is still running, sending kill signal"
        Process.kill("KILL", pid.to_i)
      end
    end
  end
end